A certain type of 2-(halogenated hydrocarbon substituted)-5-benzyl-1-azolylmethylcyclopentanol derivative is described in Patent Document 1 as a compound that can be used as an active ingredient for agricultural and horticultural chemicals, industrial material protectants, and the like. A method of producing a 2-benzyl-5,5-bis(hydroxymethyl)-cyclopentanone derivative having a protected hydroxy group from a 1-benzyl-2-oxocyclopentane carboxylic acid alkyl ester derivative, which is a -ketoester compound, is also described in Patent Document 1 as a part of a step in the production method of this derivative.